The villain in Cast Away is nature.

Delivering the package is a motivation to get off the island. He thinks if I get off this island, I will provide this to its rightful owner to symbolize his gratitude for living and loyal to his job. FedEx should have paid him 5 million because he returned it. By the way, 5 million was the perceived net worth of Chuck Nolan, the real castaway. Moreover, the wife had little to do with his motivation. He secretly did not like his wife after discovering that she buried "him" without a body.
Cast Away's climax builds when he leaves the island and is floating in the sea. The actual climax is when he loses Wilson (floating away), lying there thinking that he lost his best friend and will die (all hope lost). After the wave that seems to mark his end, we are taken off the intense climax by relief of the grandeur boat that saves his life.
The resolution is the action of delivering the package. Is the aftermath of everything put in order, at least in Tom's mind. 
The end is the classic Ernest Hemingway's the 'crossroad' less traveled. Since the main character has experienced such a usual life experience, the audience should expect he takes the less traveled road, no longer afraid of uncertainty and loneliness.
Cast Away is a significant movie, from the toothache to the coconut, the SOS signals, to the wild waves.